Humic substances (HS) are ubiquitous in nature and arise from the decay of plant and animal residue in the environment. HS are among the most widely distributed natural products on the surface of the earth, and are the major organic components of soil (humus), lakes, rivers and geological deposits such as peat, leonardite, lignite (brown coal), and organic clays. Humifed organic matter (HOM) is relatively stable, but can vary in composition based on its location, deposit type, depth, and age. HOM contains a complex mixture of organic molecules, such as bioactive polyelectrolytes (BPs).
BPs include numerous bioactive, naturally occurring, related, but not identical, high molecular-weight polymers. Examples of BPs include, but are not limited to, fractions of HS, such as humic acid (HA), fulvic acid (FA), humin, or ulmic acid (UA). The differences among BPs include a considerable variation in molecular weight and size, the number of functional groups (e.g., carboxyl, phenolic HO), and the extent of polymerization that has taken place. HA and FA have received broad international attention within the scientific community due to their wide range of bioactive characteristics. See, e.g., Drozd J., 1978, Studies of chemical and physiochemical properties of humus compounds of some taxonomic soil units, Rosprawy Naukowe, Zeszyt 13, AR Wroclaw pp. 65. BPs are useful for multiple functions in humans, other animals, and plants.
Despite extensive research directed to understanding the formation and composition of HOM, the precise chemical structure of the constituents of HOM remains unknown. HOMs that have been isolated from different sources experienced different environments, oxidative states, and humification processes; thus they typically exhibit widely varying compositions. These variations result in the production of a vast and complex array of BPs that range in molecular weights from 60 to 300,000 Da and whose polymers vary in length from a few nanometers to several microns.
Certain HS, such as peat-derived bioactive products, have been used for treating skin and other conditions. The skin is the largest organ and its primary function is to serve as a protective barrier against outside environment and excessive water loss. Skin consists of two main tissue layers: a keratinized stratified epidermis and an underlying thick layer of collagen-rich dermal connective tissue providing support and nourishment. Impaired wound healing is a major complication underlying several disease processes (such as diabetes). Efficient wound healing is hampered by a wide variety of processes including hypoxia (oxygen deprivation), inflammation, infection, and oxidative stress through the generation of harmful reactive oxygen species (ROS). The inherent complexity of wound healing has resulted in limited efficacy of most therapies that target single parameters involved in the slow healing processes.